Tensile loss measurement

Loss of elongation is the most sensitive criterion for aging measurement regardless of mechanism, and it is favored over measurement of tensile loss for cured compounds. In synthetic mbber production (SBR, in particular), viscosity increases with aging and can affect processing if not prevented. 

The oriented film specimens were mounted on aluminum frames and exposed on an Atlas Weather-Ometer, Model 65WR. An 18 minute spray cycle together with an 102 minute cycle at 55% relative humidity and approximately 65°C was used. At regular intervals, the test specimens were removed from exposure and their tensile strength measured on an Instron Model 1102. A decrease in tensile strength, expressed as tenacity, over the tensile strength of the same formulation before exposure, is a measure of the deterioration of the physical properties of the polymer. "Failure" in this test is defined as a loss of 50% or more of the initial sample tenacity. 

Ecker (232) has shown that laboratory abrasion loss data may be related to tensile strength measured at 100° C and e= 150 sec-1. The resulting plot is a band of experimental points, the width of which along the abrasion loss axis nowhere exceeds + 20% from its center. To obtain closer correlation it is necessary to consider also the coefficient of friction and the viscoelastic properties of the rubber (232). Sliding friction and viscoelasticity in rubbers are closely related (233). 

Figure 13. Excess microbending losses measured in the experiment of Figure 12 for various single mode and multimode fibers as a function of the 30-min, 23 °C tensile relaxation modulus of the coating material. The relaxation modulus-time relationships of the coating materials are depicted in the inset. (Reproduced with permission from Ref. 6. Copyright 1980 IEEE.)...

Comparison with Other Metals. Other metals were exposed to the same weathering environments over the same time periods used to evaluate corrosion of aluminum alloys. Comparative corrosion rates (average loss in thickness per side calculated fiom weight losses measured after exposures of 10 and 20 years) are listed in Table 7 for aluminum, copper, lead, and zinc panels. Hgure 2 compares losses in tensile strengths at sevraal weathering sites for unprotected low-carbon steel (0.09C, 0.07Cu) and for aluminum alloys. 

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